pt. I. Pioneers of evolution from Thales to Lucretius, B.C. 600-A.D. 50.--pt. II. The arrest of inquiry, A.D. 50-A.D. 1600: 1. From the early Christian period to the time of Augustine, A.D. 50-A.D. 400. 2. From Augustine to Lord Bacon, A.D. 400-A.D. 1600.--pt. 3. The renascence of science, A.D. 1600 onward.--pt. IV. Modern evolution: 1. Darwin and Wallace. 2. Herbert Spencer. 3. Thomas Henry Huxley